Jackets and other outerwear often incorporate a fabric liner. The liner may be part of a multi-fabric sandwich or a separate piece of fabric. Liners serve many purposes including to enhance the inside appearance of a garment and to enhance the wearability of the garment. Liner fabrics are typically thin materials, and are sized slightly larger than the lined material for some amount of “give”. This characteristic makes liners prone to bunching, and such bunching typically occurs near trimmings such as slide fasteners or zippers, thereby resulting in snagging.
Snagging also is common in Jackets and other outerwear made from heavier fabrics that use a heavier zipper. Heavier zippers have larger sliders that are more prone to snag a garment liner. In addition, lined jackets that include a stretchable waist band are particularly prone to snags since the liner has to be loose enough to accommodate the maximum stretch allowed in the waist band. Other garments may be composed of very light weight fabrics, or may include decorative elements made from light weight fabrics. Such light weight fabrics can similarly become enmeshed in the slider body of a slide fastener, causing jams.
There are numerous types of zippers, with a wide variety of sliders, used throughout the garment, equipment, and accessory industries. Typical slide fasteners comprise metal zippers, molded zippers, and coil-type zippers. In each case, the zippers used in various products (garments, outdoor/camping equipment, bags, etc.) tend to be of a larger size such as a number 5, 6, or 7. While the larger size does not itself make a slider more prone to jams, the larger size sliders have larger openings into which fabric can wedge.
Conventional zippers are also prone to snagging due to the geometry of the slider (the size of the throat openings, the tight tolerances between the side rails and the zipper teeth, the overall tolerances between the throat openings and the size of the zipper teeth), and the rotation imparted to the slider body when the pull tab is pulled to close the zipper. This rotation causes the slider body to rotate towards the liner fabric, and therefore increases the likelihood of a snag. While this rotation is less pronounced with a larger size zipper, as mentioned above, the larger size is more prone to snagging because of the larger openings in the slider body.